flow status should indicate the number of files checked #863
Description
TL;DR: Instead of No errors!, Flow should say something like No errors! (Checked 1,234 files).
I recently noticed that vim-flow was getting borderline annoyingly slow. Whenever I saved, it took ~3 seconds for me to get control of my cursor back.
I could reproduce this on the command line in my project:
$ echo '' >> src/main/GeneTrack.js; time flow status
No errors!
flow status 0.41s user 0.10s system 19% cpu 2.567 total
I had 81 files in my repo and I was using Flow 0.16.0:
$ git ls-files | grep '\.js$' | wc -l
81
$ flow --version
Flow, a static type checker for JavaScript, version 0.16.0
Eventually I discovered the reason that Flow was slow: it was scanning over a ton of irrelevant files in node_modules:
$ flow check --verbose 2> /tmp/flow-all.txt
$ grep -o 'pileup.js/node_modules.*' /tmp/flow-all.txt | perl -pe 's/:.*//; s/[\\]?".*//; s/ .*//' | sort | uniq | wc -l
11729
I tried adding this to my .flowrc, but it produced many errors:
[ignore]
.*node_modules/.*
I wound up using this command to find the worst offenders:
$ grep -o 'node_modules.*' /tmp/flow-all.txt | perl -pe 's/:.*//; s/[\\]?".*//; s/ .*//' | sort | uniq | perl -pe 's,node_modules/([^/]+)/.*,$1,' | uniq -c | sort -nr
2012 grunt-browserify
1758 watchify
1554 browserify
919 istanbul
800 fabric
593 grunt-contrib-uglify
541 react-tools
534 sniper
307 jstransformify
268 react
and I blacklisted them in my .flowconfig:
[ignore]
.*node_modules/grunt-browserify.*
.*node_modules/watchify.*
.*node_modules/browserify.*
.*node_modules/fabric.*
...
Now I'm down to a mere 1228 files checked. flow status runs dramatically faster: 0.5s instead of 2.5s.
I suspect there are many Flow users who don't realize that they have a ton of node_modules slowing them down. Adding a less roundabout way to get at the number of file checked would encourage users to deal with this. One way would be to add a file count to the No errors! message.